GMNA GM6433M PDF

This standard describes the requirements of commercial gaskets used in automotive engine cover applications. Engine oil pan gaskets are specified in GMW3083. The constructional and component features covered by this commodity standard are described below.

Compound Description. Table 1 through Table 3 contain requirements for all gasket compounds. Specific compounds can be assigned a type (see last paragraph of subsection 1.1.1) as in Type 1 and 1A, silicone (VMQ) rubber. Part performance requirements are in Subsection 4.2 and Table 4. See 1.4 Remarks.

Compound Identification. The gasket compound functional temperature limits and design are described below by the specific temperature condition letter and production release construction code. These upper temperature limits are based on the fluid media requirements and do not necessarily represent the upper limit of the approved compound.

Condition A: All approved silicone (VMQ) gasket compound(s) with a functional temperature range of –40°C to 150°C. The limits are defined by ASTM D1329 TR10 and the continuous upper temperature limit (CUTL) by SAE J2236.

Condition B: All approved polyacrylate (ACM) gasket compound(s) with a functional temperature range of –22°C to 150°C are defined by ASTM D1329 TR10 and SAE J2236 respectively.

Condition C: All approved hydrogenated acrylonitrile-butadiene (HNBR) gasket compound(s) with a functional temperature range of −18°C to 135°C are defined by ASTM D1329 TR10 and SAE J2236 respectively.

Condition D: All approved fluorocarbon (FKM) gasket compound(s) with a functional temperature range of −15°C to 175°C are defined by ASTM D1329 TR10 and SAE J2236 respectively.

Condition E: All approved ethylene propylene diene monomers (EPDM) gasket compound(s) with a functional temperature range of −35°C to 125°C. The limits are defined by ASTM D1329 TR10 and the continuous upper temperature limit (CUTL) by SAE J2236.

Within a compound temperature condition code (A through E), additional compounds can be further designated by type. The main factors considered for type distinctions include: (a) recognition of a distinctly different compound property profile, influenced by process, cure, and/or hardness, within a compound nomenclature class (ASTM D1418); (b) recognition of design and process influences on compound property selection; and (c) to separate different end use requirements (base engine vs. turbo or supercharged).

Compound Nomenclature. Identify your type using ASTM D1418 or ISO 1629. Symbol. Plastic and rubber parts shall be marked with a symbol to designate the type of compound from which the part was fabricated for the purpose of collection and handling of parts of recycling.

Elastomer Marking Symbol. Mark rubber parts weighing more than 200 grams per ISO 1629. Marking size and location per SAE J2332.

For Example: Polyacrylate >ACM<

If practical, place the part number, your company Rubber Manufacturer's Association (RMA) code, cavity number and mold date (mm/yr) on the part. Characters shall be visible, and not in a location that adversely affects form, fit, or function.

Plastic Marking Symbol. Mark plastic parts weighting more than 100 grams per ISO 11469. Marking size and location per GM7400M.

For Example, Polyamide with glass fibers >PA-GF30<

Typical Application. Gaskets or seals for front and rear covers, cam and rocker arm covers and spark plug well.

Remarks.

Approved compound properties for each elastomer class are listed in Tables 1 through 4. Table values are a compilation of data from one or more compounds. Compounds will be removed from the list as they are replaced by better, more cost effect ones.

All approved compounds successfully completed GMW3155 in polyalpha olefin (PAO) synthetic engine oil without physical damage or significant hardness change. Moderate to high compression set was observed in some fixture tests. Design is a critical factor for successful sealing particularly when selecting the VMQ compounds. If properly protected and compressed, VMQ is a satisfactory performer. Beware of engine conditions prone to consistent oil dilution with fuel (≥5%).

Although not oil resistant, the approved EPDM compound is used only in unique designs where coolant passages in an oil environment are part of the gasket function. The EPDM has 150°C temperature capability, although the media system (table) requires a lower functional limit. EPDM is not to be used for sealing oil.

There is a misconception that any compound successfully completing GMW3155 is acceptable for future applications independent of design considerations. Satisfactory GMW3155 test results are compound and design dependent.

Silicone rubber seal compounds approved to this standard are safe for use near oxygen sensors (comply with GM9009P limit) and do not contribute to oil foaming (complies with Subsection 4.2.1.7). Parts made from silicone rubber approved to this standard are not post cured.